/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.orc;

import org.apache.flink.orc.vector.OrcLegacyTimestampColumnVector;
import org.apache.flink.orc.vector.OrcTimestampColumnVector;

import org.apache.hadoop.hive.ql.exec.vector.ColumnVector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Util class to handle timestamp vectors. It's responsible for deciding whether new or legacy (Hive 2.0.x) timestamp
 * column vector should be used.
 */
public class TimestampUtil {

	private TimestampUtil() {
	}

	private static final Logger LOG = LoggerFactory.getLogger(OrcLegacyTimestampColumnVector.class);

	private static Class hiveTSColVectorClz = null;

	static {
		try {
			hiveTSColVectorClz = Class.forName("org.apache.hadoop.hive.ql.exec.vector.TimestampColumnVector");
		} catch (ClassNotFoundException e) {
			LOG.debug("Hive TimestampColumnVector not available", e);
		}
	}

	// whether a ColumnVector is the new TimestampColumnVector
	public static boolean isHiveTimestampColumnVector(ColumnVector vector) {
		return hiveTSColVectorClz != null && hiveTSColVectorClz.isAssignableFrom(vector.getClass());
	}

	// creates a Hive ColumnVector of constant timestamp value
	public static ColumnVector createVectorFromConstant(int batchSize, Object value) {
		if (hiveTSColVectorClz != null) {
			return OrcTimestampColumnVector.createFromConstant(batchSize, value);
		} else {
			return OrcLegacyTimestampColumnVector.createFromConstant(batchSize, value);
		}
	}
}
